In recent years, with rapid development of the electric power system, short circuit current level of the system increases dramatically, and the increased short circuit current level results in serious consequences to the power grid, which restricts development of the electric power system. Therefore, effective measures must be taken to limit the short circuit fault current.
As a solution for limiting the short circuit fault current, the fault current limiter can effectively limit the short circuit current lever in the power grid. The fault current limiter has the following advantages: on the one hand, dynamic and thermal stability load of various high-voltage electrical equipment such as a circuit breaker can be reduced to ensure safety and stable operation of the power grid; and on the other hand, design capacity of the power grid structure can be remarkably reduced. Thus, it is of great practical significance and application value to develop a novel fault current limiter which is excellent in performance and economically reasonable.
Currently, there are several types of fault current limiters as below: (1) a fault current limiter in which a current limiting reactor is connected into the system in series, but the series-in inductance may increase normal running impedance of the system, thereby affecting transmission capacity and operation stability of the system; (2) an inductive superconducting fault current limiter, but hidden danger that the transformer bears a too large short-circuit current and is saturated in magnetic flux is required to be avoided in the current limiting process; (3) a solid-state fault current limiter which is divided into a switch type solid-state fault current limiter and a resonance type solid-state fault current limiter, but the switch type solid-state fault current limiter has a relatively high cost while requiring a extremely high response speed of the protection circuit, and the resonance type solid-state fault current limiter introduces inductor and capacitance elements, which increases possibility of generation of oscillation and overvoltage in the system; and (4) an arc current transfer type fault current limiter, but it limits the fault current by a current limiting resistance, and thus has a resistance heating problem under the current-limiting operating condition. Thus, application of the above current limiting schemes in an actual system is limited due to various defects.